Attachment for turning work pieces by means of broad cutters



Nov. 10, 1931. F. MULKA 1,330,881

' ATTACHMENT FOR TURNING WORK PIECES BY MEANS OF BROAD CUTTERS Filed July 2. 192a s Sheets-Sheet 1 //7 wanton: [2 Ff/Fdf/Zl? Mu/ka' W Nov. 10, 1931. F. MULKA 1,830,881

ATTACHMENT FOR TURNING WORK PIECES BY MEANS OF BROAD CUTTERS Filed July 2. 1928 s sheets-sheet 2 |c Ci Ch new; a Q B 1 1-! I I 'LJiLp'LJ e b b i b I j-iffff lilI-f Fi 5a. F1375 /n venzor:

F. MULKA Nov. 10, 1931.

ATTACHMENT FOR TURNING WORK PIECES BY MEANS OF BROAD CUTTERS Filed July 2. 1928 3 Sheets-Sheet 3 /n ven zon: fi/kdn'ch Mal/ a Lax-M Patented Nov. 10, l 931 UNITED STATES PA E TO C FRIEDRICH MULKA, or, SUHL, -.GERMANY A'ITACHMENT ron. TURNING wonx rrnons BY MEANS or BROAD onr'rnns Application filed July 2, 1928, Serial No; 289,834, and in Germany July 6, 1927.

The present invention relates to a process for turning work-pieces by means of broad cutters. The noveltyand fundamental subject of the invention consists therein, that in themselves known broad cutters are connected in groups and that the individual broad cutters of a group are acting upon equal. length of the work-piece, respectively take off chips of equal width. In order, that the acting forces may be compensated reciprocally, the broadcutters of one group are-so arranged, that their center-lines are located exactly, or approximately so, in one plane. It-is hereby enabled to take off a considerably greater chip-cross-section under equal cutting-velocity. By this process, work can on an average be done in one tenth of the time hitherto required and the increase in capacity is therefore extraordinarily great. It is but natural, that the piece of metal can simultaneously be worked by a number of groups of broad cuttersto enable working upon greater length. According to the present invention, the broad cutters are only moving radially. Under such radial movement is however not only understood the absolutely rectilinear movement from the periphery towards the center, but all oscillating motions of the workpiece fromoutward to the inward, even though these movements may not be perfectly rectilinear. p

The technical progress of the process consists therein, that oscillations cannot arise even with excessivelybroad chips andthat the turning-tool can be moved with the same feeding-velocity employed in longitudinal turning for roughing. Oscillation can not arise,as the tools, actingfrom all sides upon the work-piece, prevent a deflection ofthe work-piece under the feeding-pressure and that the force of the cutting-pressure, having a tendency to produce oscillations, can not become. effective, as several, 8 different chip-cross-sections are turned off simultane ously, so that in-a part of the turning-tools ,lations.-' V

The considerable saving of time,.-. or the considerablel'increase in capacity sunder equal consumption of time, is based therean increase in cutting-pressure and in another part of the turning-tools a decrease in the cutting-pressure is being produced. These periodical, reciprocal effects'arise consequent to the separation of different chipcross-sections.

A feeding-velocity, as in longitudinal turning, can, according to the present invention-be obtained by means of cross-cutters for v the reason, that difi'erent tools work. in different planes andiare' consequently working withoutlateral friction and free fromoscilupon, that considerably larger chip-crosssections can be taken off, than would be possible according to theknown process, even under most economical working;

An idea of the capacity of a lathe is formed the ratio of feeding-distance to length of turning. While in turning with a turning-tool, moved in the longitudinal direction of the work-piece, the. greatest depth of cut is, under most favourable conditions equal to workpiece-diameter minus diameter of the piece to bewturned-on, divided by two and while the feeding-distance must correspond to the'length of turning,'the width of cut can, by the novel process, be equal to a'multiple of the workpiece-diameter,"i. e; 1n many instances equal to'the length of If it is a question of taking off a chip "of 3 mm; thickness for a lengthto be turned of mm., the feeding-distance is, according to the above arguments in the known process 30 mm., in the new process however only 3 mm., so that an increased capacity of 30 3=1O is obtained, i. e. only one'tenth part of the time is required, or ten times the length can be turned in the same time by working in accordance with the novel process. Hereby it is naturally supposed, that the employed cutters are having a total width of 30 mm. and that the feeding-velocity is in both cases equal.

This increase in capacity obtained under equal number of revolutions of theworkpiece during working, can considerablybe increased thereby, that the number of revolutions of the work-piece is increased at the ratio, in which the diameter of the. workpiece is being reduced during working, so that the highest cutting-velocity is always maintained.

Another considerable advantage of the new process consists therein, that the specific consumption of power is smaller as in the hitherto known process for the reason, that the feeding pressure and the cutting-pressure are not straining the spindle of the lathe. In turning by means of tools moved in longitudinal direction, the longitudinal bearing is loaded by the feeding-pressure and the cross-bearing of the lathe-spindle by the main cutting-pressure.

Devices for the novel process are illustrated schematically in the accompanying drawings. i

Fig. '1 is an end-view of' the faceplate carrying the turning-tools and the bar of material to be'turned. 7

Fig. 2 is a side-elevation of Fig. 1.

Fig. 3 shows the manufacture of a cylindrical pivot; I

Figs. 4, 4a and 46 show the arrangement of two groups of'broad cutters, wherein the broad cutters are staggered by 180.

Figs. 5 and 5a show one embodiment of the invention relative to the arrangement of tools, with three broad cutters.

Fig. 6, 6a and 6?) show constructions modified compared with the construction according to Fig. 1.

Fig. 7 shows an. arrangement with auxiliary supports.

On the face-plate a, four tools, Z), 0, cl, and e are i. i. provided. Therod f of the material to be worked, is passed through the face-plate a. The turningetoolsb, 0, (Z and care moved vertical to the axis of the revolving workpiece f. The turning-tools b and (Z are employed for roughing thegrooves 7. These tools are provided with. two teeth 6 respectively d. The tools 0 and e serve for taking off the remaining parts h from the workpiece. The tools I) and (Z commence and finthe: finishing cut.

In the tools 6 and (Z, a comparatively small lateral pressure arises during working at the ends of the teeth I), as the same can be designed. oblique and as the depth of out, amounting to only 1 to 1 feed depth per revolution, remains constant.

Dividing the chip according to Fig. 3 enables, that the left hand tooth of the tool 6 cuts with both edges, while the right hand tooth of the tool 6 and the teeth of the tool (Z are cutting with one edge only. The tools cand ehowever are working perfectly unobstructed, as they are only separating the ribs 71... V The constructions, embodying the process according-to Figs. 4-7, show groups of broad cutters, whereby the steel is worked symmetric and concentric. This has'the advantage, that the work-piece is acted upon by the broad cutters from all sides, so that the work-piece centers itself automatically between the broad cutters. Atorsional strainfis consequently only exerted upon the work-piece-and working can therefore be done with-comparatively very broad cutters.

In Fig. 4 working is efiected for a certain length by two groups staggered by 90, wherefrom each two opposite disposed broad cutters belong to one group. Corresponding thereto, the broadcutters b and c belong f. i. to the first group and the broad cutters d and e to the second group. The, broadcutters b and c are staggered in oneplane cZ-d by 180. The broad cutters cl andew are disposed in a secondplane B.-B, staggered by 180, the said plane being twisted comparedto the plane AA, by 90. The center-line I-II of the group of broad cutters b, 0 can be staggered, relative .to the center-line III IV of the group of broad cutters d, e- V In Fig. 5, working of a certain length is effected by one group of three broad cutters belonging together, being each staggered to one-another by 120. Fig. 5a shows in what manner the working-breadth of the individual cutters are staggered towards each other.

Fig. 6 shows the working by one group of four broad cutters, belonging together,

staggered by 90 each.

Fig. 7 shows working of a greater breadth with two broad cutters only, staggered towards each other by 180. The broad cutter 1 is designed as multiple-tool cutter, the

broad cutter 2preferably as solid cutter. To

prevent fluctuations in the work-piece, two supports, 7' and g, staggered towards each otherby 180, are t. i. designed as rollersand simultaneously fed forward radially with the broad cutters. This construction has the advantage, that only two broad cutters are required forworking one length to be turned. In all the illustrated arrangements, equal length, respectively equal chip-cross-sections are separated by the broad cutters belonging together. The. feeding press'ure, according {55 one-another by half the width of tooth b orto Fig. 7 is hereby f. i. compensated in radial direction and the main cutting-pressure in vertical direction. Dividing the width of chips enables generally in everyone of the 5 multiple cutting-edges to convert the oscillating forces of the cutting-pressure'into a constant force. 7

It has been proved particularly practical, to make the individual edges of the multiple cutters of different width, so that these individual edges are taking off differently large chip-cross-sections.

Different values of oscillations are hereby rious edges, whereby the total pressure of all cutting-edges exerts itself with greatest certainty as constant force upon the workpiece. The total chip-cross-section, taken off by the multiple cutter is hereby likewise by the solid cutter belonging thereto;

' In all the illustrated arrangements the broad cutters, belonging together, separate sections.

A special advantage of the present mode of embodying the invention consists therein, that one broad cutter each of a group is provided with an uninterrupted cutting-edge, as f. i. in Fig. 4 the cutters and e, in Fig. the cutter b, in Fig. 6, the cutter 6. These cutters, with a full edge, are,during roughing of the broad cutters disposed in front M thereof, only taking the remaining equal chip-cross-section off, like the other multiple broad cutters belonging thereto. After completion of the roughing-work by the multiple cutters, the same act, during 2-3 revolutions of the work-piece, as scrapers and produce thereby an extraordinary smooth working-surface, such as could otherwise.

only be obtained in presentsmachine tools by grinding.

, The above described invention can be varied within wide limits without impairing the range of the invention in itself thereby. The abstraction, width of cut, or width of chip may f. i. be considered identical, if the 0 cutter a is f. i. of greater width as the distance between I) b, as the cutter 0 is in this case only taking off the remaining Width of chip, even if the cutter 0 should itself be of greater width. In the claims, the expression 5 effective width of chip has consequently been used as general characteristics. It is likewise possible to provide the cutter 6 likewise with two edges 0 0, whereby the total of the prongs b 5 should be equal to the total of the prongs c 0. In this instance, it is possible, that the one prong 0 will be located between the two prongs b b andthe centre-lines of b and 0 would in this case not coincide perfectly, but be displaced towards produced by the cutting-pressure of the va-' the sameas the chip-cross-sectiontaken off.

equal length, respectively equal chip-cross- 0- ,flhese. and similar constructions shall be understood as coveredbythe claims. 7

:I-claima 21. A turningattachment comprising a plurality of radially movable broad cutters symmetrically arranged around the work-piece, each ,ofwhich cutters is adaptedto take off an equal, chip cross-section from the said work-piece and ,befsimultaneously moved cuttingoperation. I 2. {A turning attachment comprising a plurality of radially movable broad; cutters forming a group, whichfcutters are symmetra'dially withthe same velocity fduring the of which is adapted'to take off equal chiprically arranged in one plane vertical to the axis of and around the-work-piece, and each cross-sections from the said Work-piece, said cutters having an equal and simultaneous radial movement during cutting operation.

A turning attachment comprising a plurality of group cutters, each containing plural radially movable broad cutters, the cutters of one group being symmetrically arranged so. as to exert their cutting force. in one plane vertical to the axis of and around the work-piece,the cutter groups being arranged one after' another lengthwise to the axis of the work-piece, said cutters being radially movable during the cutting operation.

4- A turning attachment comprising a plurality of radially movable broad cutters symmetrically arranged in groups around the,work-piece,'each ofwhich broad cutters comprises a plurality of cutting teeth, which teeth of a single cutter are displaced symmetrically to the teeth of the other broad cutters of the same group, said cuttersbeing radially movable during the cutting operation.

5. A turnlng attachment comprising a plurality of radially movable broad cutters symmetrically arranged in groups around the workpiece, certain of which broad cutters comprise a series of cutting teeth of different width, the total width of which is equal to the total Width of each other broad cutter belonging to the same group, said adapted to remove equal chip-cross-sections from the work-piece, said cutters being radially movable during the cutting operation. r

7 A turningattachment comprising a plurality of broad cutters symmetrically disposed about the Work-piece, said cutters extending the full length of the Work-piece and adapted to be radially moved with respect to the said work-piece, certain of said cutters having a plurality of cutting edges of unequal widths tending to break up the V turning oscillations produced by the cutters into oscillations of unequal frequencies counteracting each other whereby to increase the cutting stability, and said cutters being radially movable during the cutting operation.

In testimony whereof I have afiixed my signature.

FRIEDRICH MULKA. 

